Achieving saturated red photoluminescence and electroluminescence with readily synthesized maleimide-arylamine copolymers

Maleimide-based red fluorescent copolymers were easily synthesized from palladium catalyzed polycondensation of N-alkyl-3,4-bis(4-bromophenyl)maleimide with commercially available or readily prepared secondary aryldiamines. The copolymers were characterized by gel permeation chromatography, differential scanning calorimetry, cyclic voltammetry, UV-vis absorption, and fluorescence spectroscopy. They showed brilliant red fluorescence in solution (toluene) with emission maximum in the range of 617-638 nm, although severely red-shifted in thin films. With judicious selection of aryldiamine monomers, the red-shifting of the thin film fluorescence can be largely diminished. The structure and property (molecular weight, glass transition temperature, and fluorescence) relationships were analyzed and deciphered as well. A light-emitting device has been fabricated with maleimide-arylamine copolymer in demonstrating the potentials for saturated red polymer light-emitting diodes (PLEDs).